What happened, in summary

A 49-year-old man presented with rectal bleeding and was diagnosed with stage IIIA, cT2N1M0 rectal adenocarcinoma. PET-CT showed the rectal tumor and regional lymph nodes but no liver, lung, or bone metastases. Because several retroperitoneal nodes also raised concern, treatment began with three cycles of neoadjuvant FOLFOX-4, followed by capecitabine-based chemoradiation using tomotherapy.

He then underwent robotic anterior resection with ileostomy. Surgical pathology found no residual cancer in the rectum or lymph nodes, giving a ypT0N0 pathologic complete response. Three additional cycles of adjuvant FOLFOX-4 were completed and were well tolerated.

Six months later, surveillance PET-CT identified a small inactive lesion in segment VI of the liver. His carcinoembryonic antigen and liver tests were normal, and biopsy found no malignancy. The lesion initially remained stable, but later enlarged and became metabolically active, creating renewed concern for metastatic recurrence. A second biopsy showed non-caseating granulomatous inflammation rather than cancer. Tests for tuberculosis, fungal infection, viral infection, and sarcoidosis did not identify another cause.

When the lesion continued to enlarge and a second small focus appeared, a multidisciplinary team recommended segmental liver resection for definitive diagnosis. Surgical pathology again showed non-necrotizing granulomas without malignancy, with features considered consistent with chemotherapy-related liver injury from FOLFOX and capecitabine. The case illustrates how treatment-related liver changes can closely resemble colorectal metastases even after repeated imaging, and why tissue confirmation prevented the benign lesion from being recorded as recurrent rectal cancer.